How much spending money should I plan to take when studying abroad in England

Im from Australia and going to England in July to study abroad for 6 weeks. All of my airport transfers, accommodation, breakfast (and some dinners) are inclusive in the program cost. There are also two weekends organised to travel and sight see which the university has organised and is also inclusive in the program cost. Does anyone have any idea of how much extra spending money I should plan to take over for the duration of my stay? I dont plan to shop a great deal, Id mainly just be buying food and drinks, but I want a bit of comfort knowing I have a bit of extra money to throw around in case something comes up. Can anyone who lives or has spent time in England help me out?